Reception device, communication control method in mobile communication system

ABSTRACT

A reception device for use in a mobile communication system having a mobile station and a radio base station to which transmission diversity for transmitting transmission signals using a plurality of antennas is applied in a downlink to the mobile station, is disclosed. The reception device includes a presumed probability control unit that sets a presumed probability for use in an antenna verification process of estimating a phase of the transmission signals from the plurality of antennas according to information about a channel of signals transmitted in an uplink from the mobile station to the radio base station when a closed loop transmission diversity control is performed by controlling the phase of the transmission signals from the plurality of antennas according to feedback information noticed by the mobile station to transmit the transmission signals.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reception device and a communicationcontrol method in a mobile communication system, and more specificallyto a reception device used as a downlink mobile station which effectstransmission diversity control in the mobile communication system and acommunication control method for use with a mobile communication systemincluding the reception device.

2. Description of the Related Art

Generally, “fading” occurs in wireless communication, and the fadingconsiderably degrades the transmission quality, that is, a bit errorrate characteristic.

A method for compensating for the degradation of the transmissionquality due to the fading can be a commonly known “transmissiondiversity” (for example, “3GPP TR25.214 v5.8.0”, March 2004; hereinafterreferred to as non-patent document 1). Described below is the “closedloop transmission diversity mode 1” as a type of transmission diversity.

FIG. 10 shows the configuration of the transmission unit for realizingclosed loop transmission diversity, and FIG. 11 shows the configurationof its reception unit.

By referring to FIG. 10, the transmission unit includes: a channel coder210 for inputting a transmission data sequence; weight units 211 and212; an antenna weight generator 215 for assigning a weight to theweight units 211 and 212 according to feedback information from a mobilestation; spreading units 213 and 214; a spreading code generator 216 forassigning a spreading code to the spreading units 213 and 214; andmultiplex units 217 and 218 for transmitting transmission signals to anantenna provided corresponding to antennas 1 and 2.

By referring to FIG. 11, the reception unit includes: a CPICHdespreading unit 310 for despreading a CPICH (common pilot channel)using a predetermined scrambling code and a channelization code of theCPICH in response to input received signals; a phase comparison unit 320for determining a phase difference between signals from a firsttransmission antenna and signals from a second transmission antennausing received CPICH symbols; and an FBI bit generation unit 360 forreceiving a determination result about a phase difference and generatingan FBI (feedback information) bit.

The reception unit is also constituted by including: a DPCH despreadingunit 311 for despreading a DPCH (dedicated physical channel) using apredetermined scrambling code and a channelization code of the DPCH oninput received signals; an antenna verification unit 321 for estimatingthe phase of signals from two antennas using the CPICH symbols receivedfrom the CPICH despreading unit 310 and dedicated pilot symbols receivedfrom the DPCH despreading unit 311 (hereinafter referred to as antennaverification); a channel estimate unit 330 of a first transmissionantenna for obtaining channel estimated values of signals from the firsttransmission antenna using the CPICH symbols; and a channel estimateunit 331 of a second transmission antenna for obtaining a channelestimated values of signals from the second transmission antenna usingthe CPICH symbols.

Furthermore, the reception unit is constituted by including: an RAKEcombining unit 340 of the first transmission antenna for performing RAKEcombining on DPCH symbols from the first transmission antenna; an RAKEcombining unit 341 of the second transmission antenna for performingRAKE combining on DPCH symbols from the second transmission antenna; anda DCH (data channel) channel decode unit 350 for combining the DPCHsymbols from the first transmission antenna with the DPCH symbols fromthe second transmission antenna, and then decoding a channel.

In the closed loop transmission diversity realized by theabove-mentioned transmission unit and reception unit, two transmissiondata sequences are respectively multiplied by W₁=A₁e^(iφ1) andW₂=A₂e^(iφ2) based on the feedback information (FBI) bit from the mobilestation, and then spreading is performed, and the data sequences aretransmitted.

First, a CPICH as a common pilot channel is transmitted from the twoantennas with the same carrier phase. The CPICHs transmitted from thetwo antennas are spread using the same spreading code and pilot symbolsare changed, thereby realizing orthogonalization. The reception devicegenerates an FBI bit for control of a reception carrier phase differencedepending on the reception carrier phase difference of the signalsdemultiplexed after the despreading of the CPICHs from the two antennassuch that the signal sequences transmitted from the two antennas can bein phase at the reception terminal of the mobile station, and transmitsit over the DPCCH of the dedicated physical channel DPCH in the uplinkfrom the mobile station to the radio base station. Thus, by controllingthe transmission carrier phase of the antenna 2 using the FBI bit fromthe mobile station, a bit error caused by a drop of the received signalpower due to the fading can be reduced. The transmission unit of thebase station multiplies the transmission data sequences of the twoantennas by the transmission antenna weights W₁ and W₂ generated basedon the FBI bit from the mobile station, and transmits the transmissiondata sequences multiplied by the transmission antenna weights from eachantenna.

In the closed loop transmission diversity mode 1 specified in the 3GPP(3rd Generation Partnership Project), the transmission carrier phase ofthe dedicated physical channel DPCH of the second antenna is controlledwith the resolution of the carrier phase of π/4 such that the receivedsignals from the two antennas can be substantially in phase whenreceived by the mobile station. Described below in more detail is theoperation performed when the closed loop transmission diversity mode 1is applied to the dedicated physical channel DPCH.

The transmission amplitudes of the two antennas in the slot n areA_(1,n)=A_(2,n)=1/√2, and the transmission carrier phases are φ_(1,n)=0,φ_(2,n)={±π/4, ±π/4}.

The mobile station estimates the reception carrier phases θ^(CP) _(1,n)and θ^(CP) _(2,n) of the CPICHs transmitted from the two antennas, andgenerates an FBI bit b_(n) at the slot n.

That is, at the even slot n,if −π/2≦(θ^(CP) _(1,n),θ^(CP) _(2,n))≦π/2 then b _(n)=0,otherwise b _(n)=1

At the odd slot n,if 0≦(θ^(CP) _(1,n),θ^(CP) _(2,n))≦π then b _(n)=0,otherwise b _(n)=1

The base station determines the provisional transmission carrier phaseψ_(2(n+1)) at the (n+1) slot of the DPCH at the second antenna asfollows depending on the decode result b_(n)′ (when there is no FBI biterror, b_(n)′=bn) of the FBI bit. When n is even,if b _(n)′=0 then ψ_(2(n+1))=0otherwise ψ_(2,(n+1))=π

When n is odd,if b _(n)′=0 then ψ_(2(n+1))=π/2,otherwise ψ_(2,(n+1))=−π/2

The transmission carrier phase ψ_(2, (n+1)) of the second antenna at theslot (n+1) is finally obtained by the following equation from theprovisional carrier phases of the slots n and (n+1).φ_(2,(n+1))=(ψ_(2,n)+ψ_(2,(n+1)))//2

There can be the case where an error occurs in an FBI bit in the uplink.In this case, since the base station performs transmission with acarrier phase different from that of the control command from the mobilestation, an appropriate phase control cannot be performed, therebyincreasing an error rate. To solve this problem, the mobile stationperforms the antenna verification process of estimating a transmissionweight (transmission carrier phase) at each slot of the DPCH. An exampleof the antenna verification is described in, for example, the non-patentdocument 1, annex A. 1, Antenna Verification.

Briefly described below is an example of an antenna verificationprocess. By the following equation, the antenna verification process ofthe transmission carrier phase of the second antenna is performed. Thatis, when n is even,if 2Σ(1/σ₁ ²){√2·Re(γξ^(D) _(2,n,1)′ξ^(CP)*_(2,n,1′))>ln {P(ψ_(2,n)=π)/P(Ψ_(2,n)=0)},then {ψ_(1,n)′,ψ_(2,n)′}={0,0}otherwise {ψ_(1,n)′,ψ_(2,n)′}={0,π}

When n is odd,if −2Σ(1/σ₁ ²){√2·Im(γξ^(D) _(2,n,1)′ξ^(CP)*_(2,n,1)′)>ln {P(ψ_(2,n)=π2)/P(ψ_(2,n)=−π/2)},then {ψ_(1,n)′,ψ_(2,n)′}={0,−π/2}otherwise {ψ_(1,n)′,ψ_(2,n)′}={0,π/2}

where Σ indicates a sum of l=1 to L, l is an index of path. ξ^(D)_(i,n,l)′ and ξ^(CP)*_(i,n,l)′are momentary channel estimated values ofthe DPCH and CPICH of the l-th path of the n-th slot in the transmissionantenna i, respectively, and γ indicates the ratio of the SIR (Signal toInterference Ratio) of the DPCH to the SIR of the CPICH, σ₁ ² indicatesthe thermal noise and interference power of each path, and P(·)indicates a presumed probability. For example, when it is estimated thatthe error rate of the FBI bit in the uplink is 4%, and if an FBI bitcorresponding to ψ_(2,n) is transmitted, then P (ψ_(2, n)=0)=96%.

When the antenna verification process is to be performed, φ_(2, (n+1))of the transmission carrier phase of the second antenna of the slot(n+1) is expressed by the following equation.φ_(2,(n+1))=(ψ_(2,n)′+ψ_(2,(n+1))′)/2

When the antenna verification process is not performed, a mobile stationassumes that there is no error in the FBI bit transmitted by the stationin the uplink, and performs reception in the downlink.

Generally, when there is an error in an FBI bit in the uplink, thecharacteristic of the downlink is improved when the above-mentionedantenna verification process is performed.

However, since the antenna verification process is the function ofcorrecting an error in phase control when an FBI bit is erroneous in theuplink, there is a possibility that it is determined there is an errorin phase control when there is no error in the FBI bit in the uplink andthe transmission in the downlink is performed with an appropriate phase.In this case, although the transmission is performed with an appropriatephase, the receiver receives data with wrong determination informationabout the phase, thereby increasing the error rate. Therefore, when anFBI bit error rate is low, a higher characteristic can be obtained ifthe antenna verification process is not performed at all, and theantenna verification process is recommended when the FBI bit error rateis high.

The FBI bit error rate varies depending on the transmission rate of thechannel in the uplink, a spreading ratio, a transmission time interval(transmission time interval: hereinafter referred to as a TTI forshort), the number of FBI bits, a target error rate, and a slot format.Normally, when the transmission rate is high, the FBI bit error rate islow. When the transmission rate is low, the FBI bit error rate is high.

An FBI bit is mapped over the dedicated physical control channel DPCCH,not over the dedicated physical data channel DPDCH. Therefore, when acomparison is made between a low amplitude ratio of the DPCCH to theDPDCH and a high amplitude ratio thereof, the FBI bit error rate islower when the amplitude ratio is high. The dedicated physical datachannel DPDCH indicates a data channel in a physical layer, and thededicated physical control channel DPCCH indicates a control channel ina physical layer.

Generally, when a mobile station performs the antenna verificationprocess, the antenna verification process is performed on all channels.When the antenna verification process is not performed, the antennaverification process is not performed on any channel.

There is a technology of stopping the antenna verification process whenthe status of the transmission line is good (for example,JP2004-179931A; hereinafter referred to as patent document 1).

SUMMARY OF THE INVENTION

As described above, when a mobile station communicates with a radio basestation using the transmission diversity in a downlink, it is determinedwhether or not antenna verification is performed regardless of thechannel type. Therefore, there can be the possibility that the antennaverification is performed when it is not necessary to perform theantenna verification, or it is not performed when necessary, therebyincreasing the channel error rate. In addition, when transmission powercontrol is performed, the transmission power to be assigned to thechannel is increased.

In the patent document 1, the on-off control of the antenna verificationprocess is performed depending on the up/down signals in thetransmission power control and the value of the transmission power.Therefore, it is considered that appropriate control cannot be performedbased on the channel type.

The present invention has been developed to solve the above-mentionedproblems with the conventional technology, and an object of the presentinvention is to provide a reception device and a mobile communicationsystem capable of performing control by switching on-off of an antennaverification process on each channel such that, for example, antennaverification is not performed when a channel has a low FBI error rate inan uplink and is performed when a channel has a high FBI error rate,thereby improving the quality of the channel.

The reception device according to claim 1 of the present invention foruse in a mobile communication system has a mobile station and a radiobase station to which transmission diversity for performing transmissionusing a plurality of antennas is applied in a downlink to the mobilestation, and includes antenna verification on-off control means forcontrolling on-off of an antenna verification process of estimating aphase of transmission signals from the plurality of antennas accordingto information about a channel of signals transmitted in an uplink fromthe mobile station to the radio base station when a closed looptransmission diversity control is performed by controlling the phase ofthe transmission signals from the plurality of antennas according tofeedback information noticed by the mobile station to transmit thesignals. With the configuration, control can be performed by switchingthe on-off of the antenna verification process on each channel, therebyimproving the quality of the channel.

The reception device according to claim 2 of the present invention isbased on claim 1, and the information about the channel is a channeltype, and the antenna verification on-off control means performs controlsuch that the antenna verification process is performed when the channeltype is a channel for transmission of voice. With the configuration, theon-off control is performed in the antenna verification processdepending on the channel type (for example, a packet channel, an voicechannel, etc.). Therefore, easier and more appropriate control can beperformed.

The reception device according to claim 3 of the present invention isbased on claim 1, and the information about the channel is atransmission rate of a channel, an amplitude ratio of a control channelto a data channel, a transmission time interval, a target error rate,and a slot format based on at least one of which the antennaverification on-off control means controls on-off of the antennaverification process. With the configuration, the antenna verificationprocess is performed depending on the transmission rate of a channel,the amplitude ratio of a control channel to a data channel, thetransmission time interval, the target error rate, and the slot format.Therefore, easier and more appropriate control can be performed.

The reception device according to claim 4 of the present invention isbased on claim 3, and the antenna verification on-off control meansperforms control such that the antenna verification process can beperformed when the transmission rate of the channel is equal to or lessthan a predetermined value. With the configuration, on-off of theantenna verification process can be appropriately controlled dependingon the transmission rate of a channel.

The reception device according to claim 5 of the present invention isbased on claim 3, and the antenna verification on-off control meansperforms control such that the antenna verification process can beperformed when the amplitude ratio is less than a predetermined value.

The reception device according to claim 6 is based on claim 1, andfurther includes a presumed probability control unit for setting apresumed probability for use in the antenna verification processaccording to the information about the channel. With the configuration,the presumed probability for use in the antenna verification process canbe appropriately set for each channel.

The reception device according to claim 7 of the present invention isbased on claim 6, and the information about the channel is a channeltype, and the presumed probability control unit sets a low presumedprobability when the channel type is a channel for transmission of voicesignals, and sets a high presumed probability when the channel type is achannel for transmission of packet signals. With the configuration, thepresumed probability for use in the antenna verification process can beappropriate set depending on the channel type (for example, a packetchannel, a voice channel, etc.)

The reception device according to claim 8 of the present invention isbased on claim 6, and the information about the channel is atransmission rate of a channel, an amplitude ratio of a control channelto a data channel, a transmission time interval, a target error rate,and a slot format based on at least one of which the presumedprobability control unit sets the presumed probability. With theconfiguration, the presumed probability for use in the antennaverification process can be appropriately set depending on thetransmission rate of a channel, the amplitude ratio of a control channelto a data channel, the transmission time interval, the target errorrate, and the slot format. With this configuration, the presumedprobability for use in the antenna verification process can beappropriately set depending on the transmission rate of a channel, theamplitude ratio of a control channel to a data channel, the transmissiontime interval, the target error rate, and the slot format.

The reception device according to claim 9 of the present invention isbased on claim 8, and the presumed probability control unit sets a lowpresumed probability when the transmission rate of the channel is low,and sets a high presumed probability when the transmission rate of thechannel is high. With this configuration, the presumed probability foruse in the antenna verification process can be appropriately setdepending on the transmission rate of a channel.

The communication control method according to claim 10 of the presentinvention is used with a mobile communication system having a mobilestation and a radio base station to which transmission diversity forperforming transmission using a plurality of antennas is applied in adownlink to the mobile station, and controls on-off of an antennaverification process of estimating a phase of transmission signals fromthe plurality of antennas according to information about a channel ofsignals transmitted in an uplink from the mobile station to the radiobase station when a closed loop transmission diversity control isperformed by controlling the phase of the transmission signals from theplurality of antennas according to feedback information noticed by themobile station to transmit the signals. In this process, control isperformed by switching the on-off of the antenna verification process oneach channel, and the quality of the channel can be improved.

As described above, the present invention can improve the quality of adownlink, for example, the BLER (block error rate) and requiredtransmission power, by controlling whether or not a result of theantenna verification is to be considered for each channel type.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing an example of the configuration of thereception device according to a mode for embodying the presentinvention;

FIG. 2 is a flowchart of the communication control method depending onwhether or not voice signals realized by the reception device shown inFIG. 1 is to be transmitted;

FIG. 3 is a flowchart of the communication control method depending onthe transmission rate and realized in the reception device shown in FIG.1;

FIG. 4 is a flowchart of the communication control method depending onthe amplitude ratio and realized in the reception device shown in FIG.1;

FIG. 5 is a flowchart of the communication control method depending onthe transmission rate and the amplitude ratio and realized in thereception device shown in FIG. 1;

FIG. 6 is a block diagram showing an example of the configuration of thereception device according to a variation of the present invention;

FIG. 7 is a flowchart of the communication control method depending onwhether or not voice signals realized by the reception device shown inFIG. 6 is to be transmitted;

FIG. 8 is a flowchart of the communication control method depending onthe transmission rate and realized in the reception device shown in FIG.6;

FIG. 9 is a flowchart of the communication control method depending onthe amplitude ratio and realized in the reception device shown in FIG.6;

FIG. 10 shows an example of the configuration of the transmission unitin a common closed loop transmission diversity; and

FIG. 11 shows an example of the configuration of the reception unit in acommon closed loop transmission diversity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The mode for embodying the present invention is explained below byreferring to the attached drawings. In the following explanation, anequivalent reference numeral in other drawings is indicated using thesame reference numeral.

(Configuration of the Reception Device)

FIG. 1 is a block diagram showing an example of the configuration of thereception device according to a mode for embodying the presentinvention. In FIG. 1, the device is different in configuration from thereception device shown in FIG. 11 in that an antenna verification on-offcontrol unit 370 for control of the execution or stop of the antennaverification process is added.

With the configuration, the CPICH despreading unit 310 despreads theCPICH on input received signals using a predetermined scrambling codeand a channelization code of a CPICH, and outputs resultant CPICHsymbols from the despreading to the phase comparison unit 320, theantenna verification unit 321, the channel estimate unit 330 of thefirst transmission antenna and the channel estimate unit 331 of thesecond transmission antenna. The received signals refers to signalsamplified by a low-noise amplifier, frequency converted, linearlyamplified by an automatic gain control amplifier, orthogonalizationdetected, A/D converted, band limited by a root Nyquist filter afterbeing received by an antenna.

Upon receipt of the received signals, the DPCH despreading unit 311despreads the DPCH using a predetermined scrambling code and achannelization code of the DPCH, and outputs the despread DPCH symbolsto the RAKE combining unit 340 of the first transmission antenna for theDPCH and the RAKE combining unit 341 of the second transmission antennafor the DPCH. The DPCH despreading unit 311 outputs dedicated pilotsymbols in the DPCH symbols to the antenna verification unit 321. TheDPCH despreading unit 311 can also output the dedicated pilot symbols tothe first transmission antenna channel estimate unit 330 and the secondtransmission antenna channel estimate unit 331.

The phase comparison unit 320 determines the phase difference betweenthe signals from the first transmission antenna and the signals from thesecond transmission antenna using the CPICH symbols received from theCPICH despreading unit 310, and outputs the determination result to theFBI bit generation unit 360.

The antenna verification unit 321 performs antenna verification usingthe CPICH symbols received from the CPICH despreading unit 310, and thededicated pilot symbols received from the DPCH despreading unit 311,estimates a weight coefficient by which the signals from the secondtransmission antenna are multiplied, and outputs the estimation resultof the weight coefficient, that is, a result of the antenna verificationto the antenna verification on-off control unit 370.

The channel estimate unit 330 of the first transmission antenna obtainschannel estimated values of the signals from the first transmissionantenna using the CPICH symbols received from the CPICH despreading unit310, and outputs the channel estimated values of the first antenna tothe RAKE combining unit 340 of the first transmission antenna for theDPCH. The channel estimated values of the signals from the firsttransmission antenna can also be calculated not only using the CPICHsymbols, but also using the dedicated pilot symbols received from theDPCH despreading unit 311.

The channel estimate unit 331 of the second transmission antenna obtainschannel estimated values of the signals from the second antenna usingthe CPICH symbols received from the CPICH despreading unit 310, andoutputs the channel estimated values of the second transmission antennato the RAKE combining unit 341 of the second transmission antenna forthe DPCH. The channel estimated values of the signals from the secondtransmission antenna can also be calculated not only using the CPICHsymbols, but also using the dedicated pilot symbols received from theDPCH despreading unit 311.

The RAKE combining unit 340 of the first antenna for the DPCH receivesfrom the DPCH despreading unit 311 the DPCH symbols from the firsttransmission antenna, and receives from the channel estimate unit 330 ofthe first transmission antenna the channel estimated values of thesignals from the first transmission antenna, performs RAKE combining onthe DPCH symbols from the first transmission antenna, and transmits thesignals after the RAKE combining to the channel decode unit for theDPCH.

The RAKE combining unit 341 of the second antenna for the DPCH receivesfrom the DPCH despreading unit 311 the DPCH symbols from the secondtransmission antenna, receives from the channel estimate unit 331 of thesecond transmission antenna the channel estimated values of the signalsfrom the second transmission antenna, and receives a result of antennaverification from the antenna verification on-off control unit 370,performs RAKE combining on the DPCH symbols from the second transmissionantenna, and transmits the signals after the RAKE combining to thechannel decode unit for the DPCH. When the RAKE combining is performed,the transmission antenna weight by which the transmission signals aremultiplied are considered, and the result of the antenna verification isconsidered for the antenna weight. When the antenna verification on-offcontrol unit 370 turns off the antenna verification process, a result ofthe antenna verification cannot be received. Therefore, the RAKEcombining unit 341 of the second antenna for the DPCH performs RAKEcombining with the antenna weight used when the antenna verificationprocess is off.

The DCH channel decode unit 350 receives from the RAKE combining unit340 of the first transmission antenna for the DPCH the DPCH symbols fromthe first transmission antenna after the RAKE combining, receives fromthe RAKE combining unit 341 of the second transmission antenna for theDPCH the DPCH symbols from the second transmission antenna after theRAKE combining, combines the DPCH symbols from the first transmissionantenna with the DPCH symbols from the second transmission antenna, andthen performs channel decoding. The channel decoding refers to, forexample, convolutional decoding, turbo coding, etc., and depends on thechannel coding method on the transmission side.

The FBI bit generation unit 360 receives from the phase comparison unit320 a determination result about the phase difference between thesignals from the first transmission antenna and the signals from thesecond transmission antenna, and generates an FBI bit.

The antenna verification on-off control unit 370 receives from theantenna verification unit 321 a result of antenna verification,determines on-off of the antenna verification process based on theinformation about a channel in an uplink, for example, a channel type,or based on at least one of the transmission rate of the channel type,the amplitude ratio of the control channel to the data channel, the TTI,the target error rate, and the slot format, and if it is determined thatthe antenna verification process is to be performed on the channel, theunit notifies the RAKE combining unit 341 of the second transmissionantenna for the DPCH of a result of the antenna verification.

It can be determined that the antenna verification is on if, forexample, the channel in an uplink transmits voice signals, and theantenna verification process is off if the channel type of the uplinkrefers to the transmission of packet signals.

It can also be determined that the antenna verification process is onwhen, for example, the transmission rate of the channel in the uplink isequal to or less than 32 kbps, and the antenna verification process isoff when the transmission rate of the channel type in the uplink is notequal to or less than 32 kbps.

It can also be determined that the antenna verification process is on,for example, when the amplitude ratio of the DPCCH to the DPDCH in theuplink is lower than 12/15, and the antenna verification is off when theamplitude ratio of the DPCCH to the DPDCH in the uplink is equal to orhigher than 12/15.

The on-off of the antenna verification process can be controlled basedon both the transmission rate and the amplitude ratio of the DPCCH tothe DPDCH in the uplink. For example, it can be determined that theantenna verification process is on when the transmission rate is equalto or lower than 32 kbps, and the amplitude ratio of the DPCCH to theDPDCH in the uplink is lower than 12/15, the antenna verificationprocess is off when the transmission rate is equal to or lower than 32kbps, and the amplitude ratio of the DPCCH to the DPDCH in the uplink isequal to or higher than 12/15, or the transmission rate is higher than32 Kbps.

In the explanation above, the antenna verification on-off control unit370 controls the on-off of the antenna verification process using thechannel type in the uplink, transmission rate, etc. However, since achannel in an uplink is generally symmetrical about a channel in adownlink, the on-off of the antenna verification process can becontrolled using the channel type in a downlink, the transmission rate,etc. in place of the channel type in an uplink.

(Communication Control Method of Mobile Communication System)

Next, the communication control method of the mobile communicationsystem according to the present invention is explained below byreferring to the flowcharts shown in FIGS. 2 to 5.

(Communication Control Method Depending on Whether or not Voice Signalsare Transmitted)

In FIG. 2, first in step S1, it is determined whether or not the channelof the uplink transmits voice signals, control is passed to step S3 whenit is determined that an voice signals are to be transmitted, andcontrol is passed to step S2 when it is determined that voice signalsare not to be transmitted.

In step S2, demodulation and decoding are performed without consideringa result of the antenna verification on the channel. That is, thedemodulation and decoding are performed with the antenna verificationprocess in the off state.

In step S3, the demodulation and decoding are performed on the channelwith a result of the antenna verification taken into account. That is,the demodulation and decoding are performed with the antennaverification in the on state.

(Communication Control Method Depending on Transmission Rate)

Next, the communication control method of the mobile communicationsystem according to the present invention is explained below byreferring to the flowchart shown in FIG. 3.

In FIG. 3, it is determined in step S11 whether or not the transmissionrate of the uplink is equal to or lower than 32 kbps. If it isdetermined that the transmission rate of the uplink is equal to or lowerthan 32 kbps, control is passed to step S13. If it is determined thatthe transmission rate of the uplink is higher than 32 kbps, control ispassed to step S12.

In step S12, demodulation and decoding are performed without consideringa result of the antenna verification on the channel. That is, thedemodulation and decoding are performed with the antenna verificationprocess in the off state.

In step S13, the demodulation and decoding are performed on the channelwith a result of the antenna verification taken into account. That is,the demodulation and decoding are performed with the antennaverification in the on state.

In this example, the on-off of the antenna verification process isdetermined based on whether or not the uplink transmission rate is equalto or lower than 32 kbps, but it can be determined based on thetransmission rate other than 32 kbps.

(Communication Control Method Depending on the Amplitude Ratio)

Another communication control method for the mobile communication systemaccording to the present invention is explained by referring to theflowchart shown in FIG. 4.

By referring to FIG. 4, in step S21, it is determined whether or not theamplitude ratio of the DPCCH (dedicated physical control channel) to theDPDCH (dedicated physical data channel) in the uplink is lower than12/15. The DPDCH refers to a data channel in the physical layer, and theDPCCH refers to the control channel in the physical layer.

If it is determined as a result of the determination about the amplituderatio that the amplitude ratio of the DPCCH to the DPDCH in the uplinkis lower than 12/15, then control is passed to step S23, and if it isdetermined that the amplitude ratio of the DPCCH to the DPDCH in theuplink is equal to or higher than 12/15, then control is passed to stepS22.

In step S22, demodulation and decoding are performed without consideringa result of the antenna verification on the channel. That is, thedemodulation and decoding are performed with the antenna verificationprocess in the off state.

In step S23, the demodulation and decoding are performed on the channelwith a result of the antenna verification taken into account. That is,the demodulation and decoding are performed with the antennaverification in the on state.

In this example, the on-off of the antenna verification process isdetermined depending on whether or not the amplitude ratio of the DPCCHto the DPDCH in the uplink is lower than 12/15, but it can be determineddepending on the amplitude ratio other than 12/15.

(Communication Control Method Depending on Transmission Rate andAmplitude Ratio)

Next, the communication control method of the mobile communicationsystem according to the present invention is explained below byreferring to the flowchart shown in FIG. 5.

In FIG. 5, it is determined in step S31 whether or not the transmissionrate of the uplink is equal to or lower than 32 kbps. If it isdetermined that the transmission rate of the uplink is equal to or lowerthan 32 kbps, control is passed to step S33. If it is determined thatthe transmission rate of the uplink is higher than 32 kbps, control ispassed to step S32.

In step S33, it is determined whether or not the amplitude ratio of theDPCCH to the DPDCH in the uplink is lower than 12/15. If it isdetermined that the amplitude ratio of the DPCCH to the DPDCH is lowerthan 12/15, control is passed to step S34. If it is determined that theamplitude ratio of the DPCCH to the DPDCH is not lower than 12/15,control is passed to step S32.

In step S34, the demodulation and decoding are performed on the channelwith a result of the antenna verification taken into account. That is,the demodulation and decoding are performed with the antennaverification in the on state.

In step S32, demodulation and decoding are performed without consideringa result of the antenna verification on the channel. That is, thedemodulation and decoding are performed with the antenna verificationprocess in the off state.

In this example, the on-off of the antenna verification process isdetermined based on whether or not the uplink transmission rate is equalto or lower than 32 kbps, but it can be determined based on thetransmission rate other than 32 kbps.

(Summary)

As described above, according to the mode for embodying the presentinvention, control can be performed with or without a result of theantenna verification taken into account depending on the channel type.That is, if a better characteristic can be expected for a channel withthe result of the antenna verification taken into account, the result ofthe antenna verification is taken into account. However, if a bettercharacteristic cannot be expected for a channel with the result of theantenna verification taken into account, the result of the antennaverification is not taken into account. Thus, the error rate for eachchannel can be reduced. When transmission power control is performed,the transmission power to be assigned to the channel can be reduced.

For example, as compared with a channel for transmission of voice, achannel for transmission of a packet is generally higher in transmissionrate. Therefore, the channel for transmission of voice has a higher FBIbit error rate. It is assumed that the channel for transmission of apacket has a lower FBI bit error rate. Therefore, it can be controlledsuch that the antenna verification is performed on the channel fortransmission of voice, and the antenna verification is not performed onthe channel for transmission of a packet, thereby improvingcharacteristics of both channels.

In the above-mentioned mode for embodying the present invention, theWCDMA (Wideband Code Division Multiple Access) system in the 3GPP isdescribed, but the present invention is not limited to the WCDMA, andcan also be applied to the communication system using the transmissiondiversity in other mobile communication systems, the MIMO (multipleinput multiple output) system using feedback information, and theadaptive array antenna system.

(Example of Variation)

In the above-mentioned embodiments, the reception device and thereceiving method for controlling on-off of the antenna verificationbased on the channel type in the uplink, transmission rate, etc. areexplained. In this example of a variation, the reception device andreceiving method of controlling the presumed probability of an FBI bitfor use in antenna verification based on the channel type in the uplink,transmission rate, etc. are explained.

FIG. 6 is an example of the configuration of the reception device towhich the receiving method according to the present example of variationis applied. In the reception device shown in FIG. 6, the antennaverification on-off control unit 370 is deleted from the configurationshown in FIG. 1, and a presumed probability control unit 380 is added.The operation of the antenna verification unit 321 is different from theoperation in the case shown in FIG. 1, but the same processes areperformed on other portions as in the case shown in FIG. 1.

The antenna verification unit 321 performs antenna verification usingthe CPICH symbols received from the CPICH despreading unit 310, thededicated pilot symbols received from the DPCH despreading unit 311, andthe presumed probability received from the presumed probability controlunit 380, estimates a weight coefficient by which the signals from thesecond transmission antenna are multiplied, and outputs the estimationresult of the weight coefficient, that is, a result of the antennaverification to the RAKE combining unit 341 of the second antenna forthe DPCH.

The presumed probability control unit 380 determines the presumedprobability of an FBI bit based on the information about a channel in anuplink, for example, a channel type, or based on at least one of thetransmission rate of a channel in the data link, the amplitude ratio ofthe control channel to the data channel, the TTI, the target error rate,and the slot format, and notifies the antenna verification unit 321 ofthe presumed probability.

It can be determined that the presumed probability is 90% if, forexample, the channel in an uplink transmits voice signals, and thepresumed probability is 96% if the channel type of the uplink refers tothe transmission of packet signals.

It also can be determined that, for example, the presumed probability is90% if the transmission rate of the channel in the uplink is equal to orlower than 32 kbps, the presumed probability is 96% if the transmissionrate of the channel of the uplink is higher than 32 kbps and equal to orlower than 100 kbps, and the presumed probability is 99% if thetransmission rate of the channel of the uplink is higher than 100 kbps.

It can also be determined that the presumed probability is 88%, forexample, when the amplitude ratio of the DPCCH to the DPDCH in theuplink is lower than 12/15, and the presumed probability is 95% when theamplitude ratio of the DPCCH to the DPDCH in the uplink is equal to orhigher than 12/15.

The determination of the presumed probability of an FBI bit can beperformed based on both the transmission rate and the amplitude ratio ofthe DPCCH to the DPDCH in the uplink.

In the explanation above, the presumed probability control unit 380determines the presumed probability of an FBI bit using the channel typein the uplink, transmission rate, etc. However, since a channel in anuplink is generally symmetrical about a channel in a downlink, thepresumed probability can be controlled using the channel type in adownlink, the transmission rate, etc. in place of the channel type in anuplink.

(Other Communication Control Methods)

Next, the receiving method for use with the reception device accordingto the present invention is explained below by referring to theflowcharts shown in FIGS. 7 to 9.

(Communication Control Method Depending On Whether Or Not Voice SignalsAre Transmitted)

In FIG. 7, first in step S41, it is determined whether or not thechannel of the uplink transmits voice signals, control is passed to stepS43 when it is determined that voice signals are to be transmitted, andcontrol is passed to step S42 when it is determined that voice signalsare not to be transmitted.

In step S42, the antenna verification is performed with the presumedprobability set to 96%, and the demodulation and decoding are performedwith the result of the antenna verification taken into account.

In step S43, the antenna verification is performed with the presumedprobability set to 90%, and the demodulation and decoding are performedwith the result of the antenna verification taken into account.

(Communication Control Method Depending on Transmission Rate)

Next, the communication control method of the mobile communicationsystem according to the present invention is explained below byreferring to the flowchart shown in FIG. 8.

In FIG. 8, it is determined in step S51 whether or not the transmissionrate of the uplink is equal to or lower than 32 kbps. If it isdetermined that the transmission rate of the uplink is equal to or lowerthan 32 kbps, control is passed to step S55. If it is determined thatthe transmission rate of the uplink is not equal to or lower than 32kbps, control is passed to step S52.

It is determined in step S52 whether or not the channel in the uplink isequal to or lower than 100 kbps. If it is determined that it is equal toor lower than 100 kbps, control is passed to step S54. If it isdetermined that it is not equal to or lower than 100 kbps, control ispassed to step S53.

In step S53, the antenna verification is performed with the presumedprobability set to 99%, and the demodulation and decoding are performedwith the result of the antenna verification taken into account.

In step S54, the antenna verification is performed with the presumedprobability set to 96%, and the demodulation and decoding are performedwith the result of the antenna verification taken into account.

In step S55, the antenna verification is performed with the presumedprobability set to 90%, and the demodulation and decoding are performedwith the result of the antenna verification taken into account.

(Communication Control Method Depending on the Amplitude Ratio)

Another communication control method for the mobile communication systemaccording to the present invention is explained by referring to theflowchart shown in FIG. 9.

By referring to FIG. 9, in step S61, it is determined whether or not theamplitude ratio of the DPCCH to the DPDCH in the uplink is lower than12/15. If it is determined that the amplitude ratio of the DPCCH to theDPDCH in the uplink is lower than 12/15, then control is passed to stepS63, and if it is determined that the amplitude ratio of the DPCCH tothe DPDCH in the uplink is equal to or higher than 12/15, then controlis passed to step S62.

In step S62, the antenna verification is performed with the presumedprobability set to 95%, and the demodulation and decoding are performedwith the result of the antenna verification taken into account. In stepS63, the antenna verification is performed with the presumed probabilityset to 88%, and the demodulation and decoding are performed with theresult of the antenna verification taken into account.

The present invention can determine the presumed probability of an FBIbit for each channel in the uplink to improve the quality of thechannel.

1. A reception device for use in a mobile communication system having amobile station and a radio base station to which transmission diversityfor transmitting transmission signals using a plurality of antennas isapplied in a downlink to the mobile station, the reception devicecomprising: an antenna verification unit that performs an antennaverification process of estimating a phase of the transmission signalsfrom the plurality of antennas; and a presumed probability control unitthat sets a presumed probability for use in the antenna verificationprocess according to information about a channel of signals transmittedin an uplink from the mobile station to the radio base station when aclosed loop transmission diversity control is performed by controllingthe phase of the transmission signals from the plurality of antennasaccording to feedback information noticed by the mobile station totransmit the transmission signals.
 2. The reception device according toclaim 1, wherein the information about the channel of signals is achannel type, and the presumed probability control unit sets a lowpresumed probability when the channel type is a channel for transmissionof voice signals, and sets a high presumed probability when the channeltype is a channel for transmission of packet signals.
 3. The receptiondevice according to claim 1, wherein the information about the channelof signals is a transmission rate of a channel, an amplitude ratio of acontrol channel to a data channel, a transmission time interval, atarget error rate, and a slot format based on at least one of which thepresumed probability control unit sets the presumed probability.
 4. Thereception device according to claim 3, wherein the presumed probabilitycontrol unit sets a low presumed probability when the transmission rateof the channel is low, and sets a high presumed probability when thetransmission rate of the channel is high.